60 PROTECTION OF PLANTS, 1916-17 



THE WHITE PINE WEEVIL, PISSODES STROBI, IN QUEBEC 



J. M. Swaine, Entomological Branch, Dept. of Agriculture, 



Ottawa. 



The work of this insect is probably the chief cause of distorted and 

 crooked white pine in Eastern Canada. The attack is upon young trees, 

 between five and twenty-five feet in height, and chiefly to those growing in 

 a pure or nearly pure stand or in the open. The work of the grubs kills 

 the terminal shoot on the last one, two, or even three year's growth. The 

 death of the terminal results in a special development of the uppermost 

 living whorl of lateral shoots; the most vigorous of these, one, two, or more 

 in number, assume an upright position and continue the upward develop- 

 ment of the tree, resulting in a crooked trunk, a double-top, or a multiple 

 top. Frequently these new terminals are attacked in turn and the value 

 of the tree for timber, or its beauty for ornamental purposes, entirely 

 destroyed. 



The work of the weevil has been particularly abundant in Quebec and 

 Ontario for the last five or six years, and in many localities a large percentage 

 of the young growth has been seriously injured. 



The Insect and its Stages 



The White Pine Weevil is a brownish beetle, about one-fourth of an 

 inch long, with irregular brown and white patches above, and a long slender 

 beak. 



The very small, watery-white eggs are placed, during April, May and 

 June, in the pulpy inner bark of the terminal shoots, usually just below the 

 terminal whorl of buds, in small pits bitten out by the beetle. Usually the 

 egg-pits exude a small drop of resin and are thereby easily discovered, but 

 when they are very numerous and closely placed many will be practi- 

 cally dry. The adults are readily found resting on the terminals during 

 the egg-laying season. 



The larvae are rather stout, legless, whitish grubs, with darker heads, 

 about one-fourth of an inch or less in length, found during summer feeding 

 in the bark and wood of the fading terminal shoots. 



The pupae lie each in a chip-cocoon fashioned by the grub partly or 

 entirely below the wood surface ; they are found in the faded shoots during 

 the latter part of the summer. 



